Just kind of a cuddle, which you can then see if he wants to turn it into a kiss, then a more, erm, advanced kiss
then whatever next step seems natural, etc.
I agree with emma that for the partner with the lower sex drive it can be really intimidating to just have it presented really suddenly. However if it's a natural progression from some general cuddling/kissing then all is great! Just make sure you don't try to turn every single kiss/cuddle into sex, because then even that becomes intimidating :( I doubt you would do this, though!
With DP where I'd say our sex drives are pretty matched (despite me always thinking I have a low one, doesn't seem so low now) and I've never felt pressure from him, anything goes, from a cuddle watching TV/in bed where it just develops, to him asking if I want to share a bath with him (also a good way to start things
you need a couple of hours, really, though) to him just straight out asking "Are you horny/do you want to have sex?" or saying "I'm going for a lie down, if you want to join me." or "I'm going to bed. Wake me up if you want sex."
I don't do as well with the direct asking, especially if I'm not particularly feeling it, even if I think, hmm, yeah I could go for that, it's often awkward for the first few minutes until things get going.